Apparatus for measuring viscosity



Aug. 22, 1950 M. o. KILPATRICK 2,519,378

APPARATUS FOR MEASURING VISCOSITY Filed April 26, 1946 3 Sheets-Sheet 1 INVENTOR Myra/z 0. fill/mind WM, Mm

ATTORNEYS Aug. 22, 1950 M. o. KILPATRICK APPARATUS FOR MEASURING VISCOSITY 3 Sheets-Sheet 2 Filed April 26, 1946 more (ELL f6 IND/6970)? 1950 M. o. KILPATRICK 78 APPARATUS FOR MEASURING VISCOSITY Filed April 26, 1946 s Sheets-Sheet :5

INVENTOR ATTORNEYS Patented Aug. 22, 1950 OFFICE APPARATUS FOR MEASURING VISCOSITY Myron 0. Kilpatrick, Bartlesville, Okla, assignor to Phillips Petroleum Company, a corporation of Delaware Application April 2c, 1946. Serial No. 665,046

. 1 This invention relates to an improved apparatus for measuring viscosity and more particularly to a viscosity measuring device designed ma adapted for use in association with various processing apparatus for measuring the viscosity of the liquid material during treatment.

In plant processing of various liquid materials it is desirable and often necessary to determine the viscosity of theliquld during various processing stages. For example, plugging of vessels, pumps and lines forming a part of the processing equipment are not infrequent if viscosity of the liquid under treatment in the processing system is not maintained. Viscosity control of the product during processing is also important if the desired physical or chemical reaction of the components under treatment is to be effected.

' It has heretofore been customary to remove samples of the liquid material at various points or stages in the processing system and making a viscosity determination of the withdrawn sampics by laboratory test. Many chemical liquids are highly sensitive to atmospheric humidity, atmospheric temperature, light or other factors to which laboratory tested samples are exposed and which differ from the environment of the liquid material as it moves through the processing system, with the result that laboratory tests of the withdrawn samples do not accurately establish a correct viscosity determination of the liquid in its processing environment. Laboratory tests of liquid samples are also tedious and time consuming, and before the viscosity determination can be completed, large batches of liquid materials of undesired viscosity may have already passed through the processing system before viscosity correction of the materials in process can materials undergo processing, and is particularly designed for application to or in processin vessels and lines operating under positive pressure. The viscosimeter instrument comprises a torque tube of predetermined length and torque characteristics which extends into the processing vessel and to. which a paddle wheel type impeller 8 Claims. (Cl. 73-59) 2 is fixedly attached to the extremity thereof. A hollow motor shaft of sufllcient strength and rigidity to be unaffected by the torque twist of the torque tube is secured to the torque tube and extends through the wall of the processing vessel for a distance exterior thereof. A' constant speed motor supported adjacent to the vessel wall is operably connected to the hollow motor shaft so as to drive the torque tube and the impeller contained within the processing vessel at a constant predetermined speed. A suitable closure 'cap attached to the vessel wall provides a supporting bearing for the motor shaft and prevents leakage of the liquid materials around the rotatable motor shaft. A strong rod is contained within the hollow torque tube and motor shaft and the inner end thereof is securely attached to the impeller. The rod is sufficiently sturdy to resist torque twist and will accurately reflect the rotation of the impeller by reason of its protected position within the hollow motor shaft and torque tube.

Suitable indicating devices are attached to the outer end of the motor shaft and rod for measuring the angle of twist between the undeformed rod and the torque deformable torque tube when the impeller is rotated within the liquid. Since the viscosity of fluids is the measure of resistance to fluid shear at any temperature, a temperature indicating instrument is preferably associated with or positioned adjacent the viscosimeter instrument to accurately record the temperature of the liquid materials within the processing vessel at a point adjacent the torque tube. A graph or chart may be provided to indicate the optimum or desired viscosity characteristics of the liquid product at varying temperatures. By taking a temperature reading of the liquid product in process, the chart will disclose the optimum vis-' A cosity which the liquid product'should have at that temperatureand a reading of the viscosimeter instrument will indicate the actual viscosity of the product under treatment. If the actual viscosity of the product under treatment, as indicated by the viscosimeter instrument, varies to a critical degree from the desired or optimum viscosity as indicated by the chart, steps can be immediately taken to correct the viscosity of the liquid product under process with minimum loss of time and with a'minimum delay in produc-' tion operations, and minimum damage to the product or equipment. 1

An object of this invention is to provide an improved apparatus for measuring and determining the viscosity of liquid materials in process.

auras-1a material in process at any and all times without vention will be particularly pointed out in the claims appended hereto, the invention itself and v the manner in which it may be carried out, may

be better understood by referring to the following description taken in connection with the ac companying drawings forming a part hereof, in which Fig. l is a diagrammatic illustration of a vessel forming a part of a processing system having associated therewith as a permanent part thereof an improved viscosimeter instrument for measur-,

ing and indicating the viscosity of the liquid product under treatment.

Fig. 2 is an enlarged cross sectional view of a fragmentary part "of the processing vessel and the associated viscosimeter instrument. this view showing more particularly the structural details of the viscosimeter instrument and the means by which it may be attached in a leakproof manner to the vessel wall.

Fig. 3 is an enlarged view or the exterior endof the viscosimeter instrument as viewed in the direction of the arrows 3-3 of Fig. 2, illustratin a simple form of indicator device which may form a part of the viscosimeter instrument;

Fig. 4 is a diagrammatic illustration of one form of chart which may be mounted adjacent the viseosimeter instrument to indicate the optimum or desired viscosity reading at varying temperatures for the liquid product under treatment.

Fig. 5 is an enlarged longitudinal cross sectional view of a viscosimeter instrument of somewhat modified design as it appears when attached to the wall of a processing vessel, the instrument here shown being particularly adapted for association with a photocell indicator and recorder.

Fig. 6 is a transverse cross sectional view of the viscosimeter instrument as it appears when viewed along line 8 of Fig. 5.

Fig. 7 is a face view of the background disc attached to the end of the torque tube of the instrument shown in Fig. 5.

Fig. 8 is a face view of the companion shutter disc which is attached to the end of the rod of this instrument,

Fig. 9 is a face view of the torque indicator discs shown in Figs. '7 and 8 as they appear when attached to the adjacent ends of the rotating torque tube and rod to visibly indicate the torque twist to which the torque tube is subjected during rotation.

Fig. 10 is a diagrammatic view of the photo cell indicator and recorder assembly operative to indicate as well as permanently record the torque angle to which the rotating torque tube is sub- 4 jected as visibly revealed by the cooperating indicator discs associated with the instrument.

Fig. 11 is an elevational view of another form of device which may be associated with the rod and torque tube of the instrument for indicating and recording the torque angle.

Fig. 12 is a front elevational view of the indicating and recording device shown in Fig. 11.

Fig. 13 is a transverse cross sectional view of the electrical contact discs associated with the rod and torque tube of the instrument as the same appears when viewed along line l5-I 5 of Fig. 12; and

Fig. 14 illustrates a chart of modified form which may be mounted adjacent the viscosimeter instrument to indicate the optimum or desired viscosity reading at varying temperatures for the liquid product under treatment.

Similar reference characters refer to similar parts throughout the views of the drawings and specifications.

There is shown in Fig. 1 for purposes of illustration a processing vessel l forming a part of a processing system for the treatment of liquid materials whose viscosity is to be controlled. The vessel i is connected in the processing system by an inlet conduit 2 and an outlet conduit 3, the liquid material under treatment being indicated by m as shown in Fig, 2. The vessel wall I carries a temperature recording instrument I which may be of any desired design or construction for measuring and recording the temperature of the liquid material m undergoing process in the vessel I.

7 known torque twist characteristics.

The viscosimeter it comprises essentially a torque tube .Il preferably formed of metal of A plural bladed impeller I! having flat blades [2' is fixed to the inner end of the torque tube Ii so as to form=a fixed part thereof. The torque tube Ii is connected to the end of a hollow motor shaft II which is rigidly and sturdily built of suitable metal so as to be uninfiuenced by any torque twist by reason of strains imposed thereon during rotation of the impeller I! in the liquid m whose viscosity is to be measured. A suitable constant speed motor I4 is connected tothe hollow motor shaft i3 and is mounted exterior to the processing vessel I upon a suitable supporting bracket il. When the motor i4 is thrown into operation to rotate the hollow motor shaft II, the torque tube II and its associated impeller I2 is rotated at the predetermined constant motor speed.

A sturdy rod i8 is contained within the hollow motor shaft is and the torque tube II, and has the inner end thereof firmly secured to the impeller I! so as to rotate therewith. The outer end of the rod I6 is supported by a suitable bearing i1 contained within the hollow motor shaft It. The rod i8 is preferably formed of a strong metal such as stainless steel and is of such a.

. character as not to be influenced by torque twist "when rotated by the impeller l2 driven b the motor ll through the torque tube Ii. It will be noted that the rod i0 is completely housed and enclosed within the hollow motor shaft ll of the torque tube II and is free of frictional contact therewith so that it may be freely rotated by the driven impeller ii.

A torque twist indicating device is associated with the outer ends of the hollow shaft It and angers sector shaped and which is provided with a base portion 2I which is rigidly attached as by securing screws 22 to the outer end of the hollow motor shaft IS. The face of the sector plate 28 is preferably white and may be provided with degree markings 23 in black. An indicator marker 25 having an open center is provided with a base portion 21 which is fixedly attached to the outer end of the 'rod I6. The marker 28 is provided with pointer 26 which overlies the degree markings 23 of the sector plate 20. The pointer 28 is preferably black in color. and is set to directly overlie the zero marking on the sector plate 28 when the viscosimeter instrument is not driven.

It is to be noted that when the.motor I4 is thrown into operation so as to drive the impeller I2, that the sector plate rotates in the direction of the arrow 24 as shown in Fig. 3 and the rod I8 rotates the indicator plate in the same direction as indicated by the arrow 28. However, the torque twist in the torque tube II caused by viscosity resistance to rotation of the impeller I2 will cause a corresponding angular displacement of the sector plate 20 with respect to the indicator plate 25 so that the pointer 28 will then overlie a corresponding angular marking on the face of the sector plate 20. The indicator reading can be taken by the use of a stroboscope during rotation of the sector plate 20 and the indicator plate 25. It will be appreciated that the driving motor I4 may be driven continuously, or

may be thrown into operation only when a viscosity reading is to be taken.

The torque tube II and impeller I2 may be removably attached to the wall 4 of the vessel I by the provision of a closure cap 88 which has threaded engagement with a surrounded threaded boss 3I associated with a vessel wall 4. The closure cap 30 may be provided with a laterally projecting collar 32 through which the hollow motor shaft I3 extends. The closure cap 30 may be provided with a bearing lip 33 having snug fitting contact with the outer surface of the motor shaft I3. The cavity within the collar portion 32 may be packed with a lubricating material 34 to provide a packing gland, the lubricating material 34 being inclosed within the collar 32 by a threaded screw cap 35. Thus a sealed and leakproof hearing is provided for the motor shaft I3. The closure cap 30 may be provided with suitable lugs 38 which may be manipulated by a suitable tool to attach and detach the same from the vessel wall 4 and thereby permit insertion and removal from the vessel of the impeller I2 and the associated torque tube I I.

In taking a viscosity measurement, the motor I4 is thrown into operation so as to rotate the impeller I2 and the torque tube I I at the constant motor speed. The viscosity characteristics of the liquid m contained in the processing vessel I exerts a predetermined resistance to the rotation of the impeller I! which imposes a torque strain and a resulting torque twist on the torque tube II. The angle of twist of the torque tube II can be read on the indicator device such as shown in Fig. 3 and the angle of twist observed by the use of a stroboscope. The temperature reading of the liquid m is taken from the temperature recording instrument 5 and reference is then made to the viscosity chart mounted adjacent to vessel I as shown in Fig. 4. The chart as shown in Fig. 4 has plotted thereon a temperature viscosity curve 44 which accurately indicates the desired or optimum viscosity which the liquid material should possess at varying temperatures. The

. 8 viscosity readings on the chart shown in Fig. 4 ma be plotted. in terms of torque angle or any other standard of measurement possessed by the indicator device. If the viscosity reading as taken from the indicator device varies to an critical degree from the optimum viscosity as indicated by the graph or chart, steps are taken to correct the viscosity of the liquid under treatment.

There is shown in Figs. 5 to 10 inclusive a highly desirable form of viscosity metering instrument assembly which can be advantageously employed both for measuring and permanently recording the viscosity of liquids undergoing treatment. As shown in Figs. 5 and 6, the torque tube II extends through the vessel wall 4 and carries a bladed impeller I2 firmly secured to the inner end thereof. The impeller blades I2 shown as four in number, are relatively fiat and are so designed as to impose no thrust upon the torque tube II. The torque tube II as an extension II. and a background disc 50 is detachably secured to the outer end thereof. The motor I4 is mounted on a separate tubular motor shaft I8 which encases the torque tube extension II'. The tubular motor shaft I8 is detachably secured to the torque tube I I at a point adjacent the vessel wall 4 in any suitable manner as by a threaded connection I8. Thus the torque tube II and its extension II may be easily detached and replaced. The torque twist to which the torque tube II is subjected by the rotation of the impeller l2 will be found in the length a of the torque tube as shown in Fig. 5, and torque in the tubular motor shaft I8 does not effect the reading. The torque tube II is preferably formed of metal and ofknown torque twist characteristics.

The rod I6 as shown in Fig. 5 has a threaded end I6 which permits the rod to be firmly and yet detachably secured to the hub portion I2" of the bladed impeller I2. A shutter disc 60 is attached to the outer end of the rod IS in a manner to overlie the background disc 50 attached to the adjacent end of the torque tube extension I I The rod I6 may be provided with a shoulder portion I9 against which the shutter disc 68 seats. the shutter disc being held in fixed position by suitable lock nut 65 attached to the projecting end of the rod. The rod is of such sturdy design so as to suffer no deformation during rotation. Since the rod I8 is enclosed within and protected by the torque tube II and its extension II, no appreciable strain is imposed thereon. The torque tube I6 may be easily removed and replaced when desired.

The torque tube I I and its extension I I, the tubular motor shaft I8, the rod I8 and the impeller I2 may be removably attached to the vessel wall 4 by the provision of a modified form of closure cap 44 designed to provide a non-leak connection. The vessel wall 4 has an opening 4| sufiiciently large to permit insertion and removal of the impeller I2. The vessel wall 4 has a projecting collar portion 42 surrounding the opening 4| and a flared flange 43 to which the collar 44 may be conveniently attached. The closure cap 44 is provided with a heavy body which snugly fits within the vessel opening H, the opening being sealed by a suitable gasket 41. The end of the tubular motor shaft I8 extends through the body of the closure cap 44 and fits within a sleeve bearing 48. The closure cap 44 is provided with a flared flange 45 adapted to be detachably secured to flared flange 43 of the vessel wall, as by detachable bolts 48.

The closure cap 44 may be provided with a lateraliy projecting collar 52 through which the tubular motor shaft ll extends. The collar 32 has a cavity which may be packed with a lubricating material 8|, providing a packing gland. The lubricating material I4 is enclosed by a screw cap 85 which has a sleeve bearing 35' in which the motor shaft ll snugly fits. A sealed and leak proof bearing is thus provided for the motor shaft. The closure cap 4| also provides a leak proof plugfor the vessel opening I which may be detached from the vessel wall 4 by removing the securing bolts 55.

The torque indicating device associated with the instrument shown in Fig. 5 comprises the background disc 50 firmly attached to the outer end of the torque tube extension ll and the superimposed shutter disc 60 secured to the end of the rod ii. The background disc 50, as shown in Fig. "1, has an outside face which has black and white markings. The white markings 53 appear as sector shape segments, separated by black segments 54 of substantially the same shape and size as the white segments 53. The white and black segments 53 and 54 are bordered by a black outer rim 5|, and a black inner rim 52.

The shutter disc 60, as shown more particularly in Fig. 8, is attached to the outer end of the rod I5, and is designed to overlie the black and white face of the underlying background disc 50. The shutter disc 60 has a plurality of sector shaped openings 6| cut therein which are the same shape and size as the black faced segments 54 of the background disc 50. The sector shaped openings 5| in the shutter disc 60 are spaced by sector shaped webs 52 having a black face of the same shape and size as the white faced sectors 53 of the underlying disc 50. The face of the shutter disc 50 is also rimmed by an outerv black band 53 and an inner black band 54. The nut 65 and the end of the rod IE to which it is attached, also possess a jet black face.

The shutter disc 50 is secured to the end of the rod IS in a manner so that the sector shaped openings 6| thereof are directly in alignment with the black faced sectors 54 of the background disc 50, and the black faced sectors 82 of disc 50 cover and conceal the white faced sectors 53 of the underlying disc 50, when the instrument is not in operation. When the torque tube H is rotated by the motor H, the impeller l2, rotating in the liquid whose viscosity is to be measured, imposes a predetermined twist on the torque tube ll, causing the background'disc 50 to correspondingly lag in its rotation as shown in Fig. 9. The rod I5 is so sturdily designed that the shutter disc 50 attached to the end thereof will not lag during rotation. The angular lag of the background disc 50, resulting from the torque twist imposed upon the torque tube ii, is revealed and indicated by the degree or area of exposure of the white sectors 53 thereof as made visible through the sector shaped openings 51 of the shutter disc 60, as shown more particularly in Fig. 9. The degree of torque twist to which through-the sector shaped openings 5| of theshutter disc 60 constitutes an accurate measure of the viscosity of the liquid undergoing process. and may be measured and recorded by a photocell 55 as diagrammatically shown in Fig. 10.

A constant light source 55 is provided having a directive element 51 designed to throw a confined light beam 55 against the face of the rotating shutter disc 50. The photocell 55 has an element 55 which receives lkht reflected from the area lighted by the beam 55 from the light source 55. The reflected light cone 5! from the illuminated and exposed areas of the white faced sectors 53 of the rotating background disc 55. visible through the sector shaped openings ll of the shutter disc 50, actuates the photocell 55 in accordance with the degree of white exposure. The degree of white exposure constitutes an accurate measure of the torque angle which the viscosity of the liquid imposes upon the torque tube I I when rotated by the motor I4. The photocell 55 may be a plate voltaic type or a photoemissive type cell, which cells with necessary auxiliaries are well known in the art. The photocell 55 is equipped with a dial indicator 55 from which the torque reading may be directly made. and the photocell may also be provided with devices to feed out a continuous ribbon 59 upon which a line graph 59' of the torque angle is recorded. Thus, by using this system, the torque angle is visibly indicated and permanently recorded. The torque angle indicated by the photocell 55 can be translated into terms of viscosity by the use of a suitable chart prepared to conform to the characteristics of the instrument.

There is shown in Figs. 11 to 13 inclusive a further modified form of indicating and recording system which may be advantageously employed in measuring the torque angle or torque twist to which the delicate torque tube i l is subjected when its impeller i2 rotates in the liquid whose viscosity is to be measured. The indicating and recording system, illustrated in Figs. 11 to 13 inclusive, is operatively connected to the torque tube extension ii and the rod ii of the viscosimeter instrument, and embodies the use of a rheostat and ammeter arrangement for measuring, indicating and recording the torque angle. In this system, a background disc 10 is firmly secured to the end of the torque tube extension II' and a smaller disc 15, fixed to the end of the instrument rod i5, is positioned to overlie the disc 10. The disc 10 has a center section II formed of strong but non-conducting material to which a current conducting rim I2 is firmly secured.

The companion superimposed disc 15 seats against the collar portion IQ of rod 16 and is secured thereto as by a lock nut 55. The central section 15 of the superimposed disc 15 is formed of non-conducting material and is also provided with a current conducting rim 'I'I bonded thereto. A metal pointer 18 is fixed to the conducting rim ll of the superimposed disc 15. The end of the pointer 18 is designed to slide in contact with a rheostat plate 13 of generally arcuate shape which is mounted on the non-conducting center section II of the background disc 15. The rheostat plate 13 is provided with the usual resistance wiring H which is connected at one end 19 thereof to the conducting rim II of the background disc Il.

An indicating and recording ammeter instrument all-is connected by wiring 52 and 55 to a current source of known ammeter rating, such as a battery 5i. One of the lead wires 52 is electrically connected to a contact arm 53 having a shoe or roller 84 which slides or ridesonthe conducting rim 1! of the background disc 15. The other wire 85 leads from the ammeter 9 instrument ll to a contact arm 8! having a shoe or roller 81 which rides on the conducting rim ll of the superimposed disc II.

When the viscosimeter instrument is in operation, the angle of twist, of the torque tube Ii is reflected in. a certain angle of lag in the mtating background disc III, as indexed by the superimposed disc 15 fixed to the non-deformable rotating rod II, and the rheostat plate I3 will slip rearwardly with. the rotating background disc II, as shown more particularly in Fig.-12, an angular distance which is the measure of the twist in the torque tube ii imposed by the viscosity of the liquid under measurement. Current fio'ws from the battery 8i through lead wire 82, through the contact arm 83, to the conducting rim 1! of the background disc 10, and thence into the current shunt resistance wire 14 of the rheostat plate 13. Current flows from the rheostat wire 14, through the pointer I8, through the conducting rim ll of the superimposed disc 15, thence through contact arm 86, through the lead wire 85, and to the ammeter instrument 80.

Assuming the discs 10 and I rotate in the direction of the arrows as shown in Fig. 12, it will be appreciated that the torque twist in the torque tube ll causes the background disc to slip counter-clockwise an angular distance b corresponding to the torque twist of the torque tube i i, as measured by the distance between the head ,end 19 of the rheostat wire and the pointer 18.

The resistance offered to current flow shunted through the segment of the resistance wire located in space b, is reflected by the indicating and recording ammeter 80, which may be calibrated to indicate torque angle. The ammeter 80 may be provided with a pointer 88 to visually indicate the torque angle, and may also be provided with devices to feed a ribbon 89 on which the variations in torque angle are suitably defined as by a scribe line 89'.

A modified form of chart 90 from which torque angle readings may be translated to viscosity of the liquid, as measured in centipoises at any given temperature of the liquid, is illustrated in Fig. 14. Thus by taking a temperature reading of the liquid under treatment, and a torque angle reading taken from the photocell system shown in Figs. 5 to 10 inclusive, or from the rheostat and ammeter system as shown in Figs. 11 to 13 inclusive, the viscosity of the liquid under treatment 10 l and recording the angle of displacement between the torque tube and the rod l6, and which the I ghboiztdiscloeure' will suggest to those skilled in While certain novel features of the invention have 'beendisclosed and are pointed out in the annexed claims, it will be understood that various omissions, substitutions and changes may be made by thoseskilled in the art without departing from the spirit of this invention.

What is claimed is: 1

1. A viscosimeter adapted to be associated with a vessel containing liquid in process which includes, a torque tube of .known torque twist characteristics contained within the vessel in the liquid environment, a bladed impeller fixed to said torque tube in contact with the liquid, a hollow shaft fixed to said torque tube and extending through the vessel wall, means exterior to said vessel for driving said hollow shaft at constant speed, a rigid rod extending through said hollow shaft and torque tube fixed to said impeller, and indicator means connected to saidhollow shaft and said rod operative to indicate the angle of twistof said torque tube when said impeller is rotated.

2. A viscosimeter adapted to be associated with a vessel containing liquid in process which includes, a torque tube of known torque twist characteristics contained within the liquid environment, as bladed impeller fixed to the end of the may be immediately determined from the chart 9!! shown in Fig. 14. If the viscosity of the liquid under treatment, as indicated by the chart, departs to a serious degree from the optimum desired viscosity at the recorded temperature, measures can immediately be taken to correct the viscosity of the liquid product in process as conditions require.

It will be appreciated that other means for indicating, recording or measuring the torque twist of the torque tube ll may be provided. For

example, the angle of displacement or twist between the torque tube II and the rod It may be measured by the provision of a pair of Selsyn motors. One of the Selsyn motors would have its stator connected to the torque tube ii and its rotor connected to the rod i6, and the other Selsyn motor would have its rotor connected to a suitable indicator,.recorder and controller device. With such an arrangement, the motors can be made to indicate and record as well as control the processing fiow. It will be appreciated that other electrical and mechanical devices may be employed for measuring, indicating torque tube incontact with the liquid, a rigid hollow shaft fixed to said torque tube and extending through the vessel wall, means exterior to said vessel for driving said hollow shaftat constant speed, a rod extending through said hollow shaft and torque tube having one end thereof fixed to said impeller, and indicator means exterior to the vessel for indicating the angle of twist of said torque tube when said impeller is rotated, said indicator including a torque twist indicator plate fixed to the exterior end of said hollow shaft to rotate therewith, and an indexing member fixed to the end of said rod to rotate therewith overlying said indicator plate.

3. A viscosimeter for measuring the viscosity of liquids which includes, a torque tube of known torque twist characteristics, an impeller designed to be contained within the liquid environment and fixed to said torque tube, means for driving said torque tube at constant speed, a rigid rod extending through said torque tube fixed to said impeller, and indicator means connected to said torque tube and said rod operative to indicate the angle of twist of said torque tube when said impeller is rotated.

4. .A viscosimeter for measuring the viscosity of liquids which includes, a torqu tube of known torque twist characteristics, an impeller designed to be contained within the liquid environment and fixed to one end of said torque tube, means operably connected to the other end of said torque tube for rotatin the impeller by means of said torque tube, a rigid rod extending through said torque tube and having one end thereof fixed to said impeller, and indicator means having a part operably connected to said other end of the torque tube and a part connected to the other end of said rod operative to indicate the angle of twist of said torque tube when said impeller is rotated.

5. A viscosimeter adapted to be associated with a vessel containing liquid in process which includes, a torque tube of known torque twist characteristics extending into the liquid environment,

an impeller iixed. to the interior end of the torque --tube in contact with the liquid, driving means operably connected to the exterior and of the torque tube for rotating the impeller through said torque tube at substantially constant speed, a mod extending through said torque tube having an impeller fixed to the interior end of the torque tube in contact with the liquid. a rigid hollow shaft fixed to the exterior end of said torque tube. a motor supported exterior to said vessel for driving said hollow shaft and torque tube at substantially constant speed,. a rod extending through said torque tube having the interior end thereof fixed to said impeller, and indicator means operably connected to the exterior ends of said torque tube and rod for indicating the angle of twist of said torque tube when said impeller is rotated by said motor.

7. A viscosimeter apparatus adapted to be associated with a vessel containing liquid in process which includes, a torque tube of known torque twist characteristics extending into the liquid environment, an impeller fixed to the torque tube in contact with the liquid, a rigid hollow shaft fixed to said torque tube and extending through an opening in the vessel wall, a sealed bearing assembly mounted within the opening in the vessel wall providing a bearing support for said hollow shaft, means'exterior to said vessel for driving said hollow shaft and torque tube, a rigid rod extending through said torque tube having one end thereof iixed to said impeller, and indi- 12 catorme'anshavingaparteonnectedtosaid torque tube and apartoonnectedtosaidrod for indicating the angle of twistof said torque who when said impeller is rotated by said driv- 8. A viscosimeter apparatus adapted-to be associated with a vessel containing liquid in processwhich includes, a torque tube of known torque twist characteristics extending into the liquid environment. an impeller fixed to one end of the torque tube in contact with the liquid, a rigid hollow shaft fixed to the other end of said torque tube and extending through an opening in the vessel wall, a sealed bearing assembly mounted within the opening in the vessel wall providing said torque tube when said impeller is rotated by said motor.

. HYRON O. KIIPA'IRICK.

REFERENCES (71TH) The following references are of record in th die of this patent:

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